J/ApJ/875/142 Copper abundances of Galactic bulge red giant stars (Xu+, 2019)
NLTE analysis of copper abundances in the Galactic bulge stars.
Xu X.D., Shi J.R., Yan H.L.
<Astrophys. J., 875, 142-142 (2019)>
=2019ApJ...875..142X 2019ApJ...875..142X (SIMBAD/NED BibCode)
ADC_Keywords: Stars, giant; Abundances; Spectra, optical
Keywords: Galaxy: bulge; Galaxy: evolution; line: formation; line: profiles
stars: abundances
Abstract:
Based on the medium-high resolution (R∼20000), modest signal-to-noise
ratio (S/N≳70) FLAMES-GIRAFFE spectra, we investigated the copper
abundances of 129 red giant branch stars in the Galactic bulge with
[Fe/H] from -1.14 to 0.46 dex. The copper abundances are derived from
both local thermodynamic equilibrium (LTE) and nonlocal thermodynamic
equilibrium (NLTE) with the spectral synthesis method. We find that
the NLTE effects for Cu I lines show a clear dependence on
metallicity, and they gradually increase with decreasing [Fe/H] for
our sample stars. Our results indicate that the NLTE effects of copper
are important not only for metal-poor stars but also for supersolar
metal-rich ones and the LTE results underestimate the Cu abundances.
We note that the [Cu/Fe] trend of the bulge stars is similar to that
of the Galactic disk stars spanning the metallicity range of
-1.14<[Fe/H]<0.0dex, and the [Cu/Fe] ratios increase with increasing
metallicity when [Fe/H] is from ~-1.2 to ~-0.5 dex, favoring a
secondary (metallicity-dependent) production of Cu.
Description:
Our sample consists of 129 red giant branch stars in the Galactic
bulge, and they have already been minutely discussed by
Zoccali+ (2008, J/A+A/486/177) and Johnson+ (2014, J/AJ/148/67).
The observations were carried out at the VLT-UT2 with the
FLAMES-GIRAFFE spectrograph, at a resolution power ∼20000. The
original program by Zoccali+ (2008, J/A+A/486/177) contained four
fields, but as the HR11 (spanning ∼5590-5835Å) was the only setup
including measurable copper lines, only two bulge fields,
(+5.25,-3.02) and (0,-12), were observed in the HR11, HR13, and HR15
setups (ESO3 Program 073.B-0074).
Johnson+ (2014, J/AJ/148/67) analyzed 156 giants with the final
signal-to-noise ratio (S/N) of each coadded spectrum exceeding ∼70,
and without strong TiO absorption bands. As the spectral S/Ns were
rather low for some stars, the final sample utilized here only
included 129 objects.
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table2.dat 53 129 Copper abundances of our program stars
--------------------------------------------------------------------------------
See also:
J/ApJ/530/783 : The r-process enriched giant HD 115444 (Westin+, 2000)
J/MNRAS/340/304 : [X/Fe] of Galactic disc F and G dwarfs (Reddy+, 2003)
J/MNRAS/367/1329 : Elemental abundances for 176 stars (Reddy+, 2006)
J/A+A/486/177 : Bulge field stars from FLAMES-GIRAFFE spectra (Zoccali+, 2008)
J/ApJ/681/1524 : Detailed abundances for 28 metal-poor stars (Lai+, 2008)
J/AZh/88/750 : Abundances in stars of gal. sub-structures (Mishenina+, 2011)
J/ApJ/771/67 : Abundances for metal-poor stars. II. (Ishigaki+, 2013)
J/ApJS/211/30 : Atomic data of CuI (Liu+, 2014)
J/AJ/148/67 : Abundances of 156 bulge red giants (Johnson+, 2014)
J/A+A/585/A102 : Copper abundances in solar neighborhood stars (Yan+, 2016)
J/ApJ/857/2 : Abundances in 6 metal-poor stars (Roederer+, 2018)
J/A+A/640/A89 : Galactic bulge red giants Co & Cu abundances (Ernandes+, 2020)
Byte-by-byte Description of file: table2.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 11 A11 deg Field Galactic coordinates of the Bulge field
13- 20 A8 --- Name Star identifier
22- 25 I4 K Teff [4225/5350] Effective temperature (1)
27- 30 F4.2 [cm/s2] logg [1.35/3.75] Log of surface gravity (1)
32- 36 F5.2 [-] [Fe/H] [-1.14/0.46] Metallicity (1)
38- 41 F4.2 km/s xi [0.95/2.2] Microturbulent velocity (1)
43- 47 F5.2 [-] [Cu/Fe] [-0.5/0.34] LTE [Cu/Fe] abundance
49- 53 F5.2 [-] [Cu/Fe]N [-0.35/0.38] NLTE [Cu/Fe] abundance
--------------------------------------------------------------------------------
Note (1): We directly employed the stellar parameters given in
Johnson+ (2014, J/AJ/148/67) for all of our program stars.
See Section 3.2.
--------------------------------------------------------------------------------
History:
From electronic version of the journal
(End) Emmanuelle Perret [CDS] 24-Oct-2023